button{
    width: 127px;
    padding:8px;
    background-color: #141d24;
    border-color: #357ebd;
    color: #fff;
    border-radius: 10px; /* future proofing */
    text-align: center;
    vertical-align: middle;
    border: 1px solid transparent;
    font-weight: 900;
    font-size:125%
}
.login-box form button {
    position: relative;
    display: inline-block;
    padding: 10px 20px;
    color: #03e9f4;
    font-size: 16px;
    text-decoration: none;
    text-transform: uppercase;
    overflow: hidden;
    transition: .5s;
    margin-top: 40px;
    letter-spacing: 4px
}

.login-box button:hover {
    background: #03e9f4;
    color: #fff;
    border-radius: 5px;
    box-shadow: 0 0 5px #03e9f4,
    0 0 25px #03e9f4,
    0 0 50px #03e9f4,
    0 0 100px #03e9f4;
}

.login-box button span {
    position: absolute;
    display: block;
}


.login-box button span:nth-child(1) {
    top: 0;
    left: -100%;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg, transparent, #03e9f4);
    animation: btn-anim1 1s linear infinite;
}

@keyframes btn-anim1 {
    0% {
        left: -100%;
    }
    50%,100% {
        left: 100%;
    }
}

.login-box button span:nth-child(2) {
    top: -100%;
    right: 0;
    width: 2px;
    height: 100%;
    background: linear-gradient(180deg, transparent, #03e9f4);
    animation: btn-anim2 1s linear infinite;
    animation-delay: .25s
}

@keyframes btn-anim2 {
    0% {
        top: -100%;
    }
    50%,100% {
        top: 100%;
    }
}

.login-box button span:nth-child(3) {
    bottom: 0;
    right: -100%;
    width: 100%;
    height: 2px;
    background: linear-gradient(270deg, transparent, #03e9f4);
    animation: btn-anim3 1s linear infinite;
    animation-delay: .5s
}

@keyframes btn-anim3 {
    0% {
        right: -100%;
    }
    50%,100% {
        right: 100%;
    }
}

.login-box button span:nth-child(4) {
    bottom: -100%;
    left: 0;
    width: 2px;
    height: 100%;
    background: linear-gradient(360deg, transparent, #03e9f4);
    animation: btn-anim4 1s linear infinite;
    animation-delay: .75s
}

@keyframes btn-anim4 {
    0% {
        bottom: -100%;
    }
    50%,100% {
        bottom: 100%;
    }
}